It’s often useful to create self-signed SSL certificates for testing or when you don’t need the authentication that CA signing provides. I started with Akadia’s handy tutorial on self-signing here: http://www.akadia.com/services/ssh_test_certificate.html.

The message-IDs that Exim uses to refer to messages in its queue are mixed-case alpha-numeric, and take the form of: XXXXXX-YYYYYY-ZZ. Most commands related to managing the queue and logging use these message-ids.

Most of the people use cron for scheduling tasks on hourly or daily basis. It is one of the very best tool which gives system administrators a lot of relief as computer can do their work when they are miles away from their systems.

Enabling/Disabling the cron for specific user is something which is not used by every person but could be useful for the system administrators or people who would like to put some restrictions on services which a normal user can use in a system.

As a general rule, however, do not copy the mysql system schema from one server to another. As a consequence, and as far as I know, there is no “standard” way of copying users and user privileges from one server to another.